Reduced Graphene Oxide-Anchored Manganese Hexacyanoferrate with Low Interstitial H₂O for Superior Sodium-Ion Batteries

Abstract

Low-cost manganese hexacyanoferrate (NMHCF) possesses many favorable advantages including high theoretical capacity, ease of preparation, and robust open channels that enable faster Na diffusion kinetics. However, high lattice water and low electronic conductivity are the main bottlenecks to their pragmatic realization. Here, we present a strategy by anchoring NMHCF on reduced graphene oxide (RGO) to alleviate these problems, featuring a specific discharge capacity of 161/121 mA h g at a current density of 20/200 mA g. Moreover, the sodiation process is well revealed by ex situ X-ray diffraction, EIS and Car-Parrinello molecular dynamics simulations. At a rate of 20 mA g, the hard carbon//NMHCF/RGO full cell affords a stable discharge capacity of 84 mA h g (based on the weights of cathode mass) over 50 cycles, thus highlighting NMHCF/RGO an alternative cathode for sodium-ion batteries.

Hexacyanoferrate‐Type Prussian Blue Analogs: Principles and Advances Toward High‐Performance Sodium and Potassium Ion Batteries

“…Wang et al reported the addition of RGO during precipitation of NaMnHCF. [ 133 ] Surprisingly, not only the morphology and stoichiometry of the precipitates are changed, but also the crystal water in the NaMnHCF is removed, the latter is evidenced by the structure change from monoclinic (Na 1.67 Fe[Mn(CN) 6 ] 0.9 ·1.47H 2 O) to rhombohedral (Na 1.89 Fe[Mn(CN) 6 ] 0.98 ·0.16H 2 O) and the single‐plateau electrochemical profile. However, the water removal and structure change are not observed for Na 1.83 Mn 0.83 Ni 0.12 Fe(CN) 6 /RGO prepared likewise.…”

“…With superior conductivity and large surface area, graphene and reduced graphene oxide (RGO) have been intensively used to complex with HCFs. [ 108,133,134,148,149,152–155 ] Han's group fabricated a free‐standing NaFeHCF/RGO (16 wt%) electrode by a series of protocols including liquid N 2 quenching, free‐drying and hydrazine reduction (Figure 15d–g). [ 149 ] The liquid N 2 quenching can promote self‐scrolling of the GO nanosheets into 1D nanorolls in which the NaFeHCF particles are firmly encapsulated.…”

Effect of Water and Alkali‐Ion Content on the Structure of Manganese(II) Hexacyanoferrate(II) by a Joint Operando X‐ray Absorption Spectroscopy and Chemometric Approach

“…Indeed, as a result of the porous nature of PBAs, these materials act as sponge‐like materials towards water molecules. However, the hydration degree affects the electrochemical performance sharply as substantial differences are seen in the electrochemical signature of fully or partially (presence of interstitial water) dehydrated materials . However, the effect of adsorbed water is not known.…”

Stepwise Hollow Prussian Blue Nanoframes/Carbon Nanotubes Composite Film as Ultrahigh Rate Sodium Ion Cathode

“…Interestingly, the existence of Na‐rich rhombohedral phase can be further verified by the splitting peaks at around 24° and 39° in the patterns of the sample discharging to 2.0 V. Through the patterns of all samples, the peak splitting and merging can be clearly observed due to the cubic‐rhombohedral phase transition, as schematically shown in Figure c. [ 39,40 ] Moreover, as shown in Figure 5c,d, FeHCFe nanoframes show less expansion of the crystal structure during charging up to 4.2 V, which can be confirmed by the shift angle of the (200) peak. 2θ angle of the peak of FeHCFe nanoframes electrode was increased by 0.2° upon further charging up to 4.2 V compared with the first discharging to 2.0 V, which is smaller than that of the FeHCFe nanocubes electrode (0.24°).…”